Targeting Of Potential Geothermal Resources In The Great Basin From Regional To Basin-Scale Relationship Between Geodetic Strain And Geological Structures

Conference Paper: Targeting Of Potential Geothermal Resources In The Great Basin From Regional To Basin-Scale Relationship Between Geodetic Strain And Geological Structures

Abstract

We apply a new method to target potential geothermal resources on the regional scale in the Great Basin by seeking relationships between geologic structures and GPS-geodetic observations of regional tectonic strain. First, we establish a theoretical basis for underst~dingh ow the rate of fracture opening can be related to the directional trend of faults within the regional-scale strain field. Second, we develop a s ~ ~ n - s ~ c tmuertheod ology that uses a digitized database of Quaternary fault strikes and velocities of GPS stations. Results of our s~ain-s~uctuarnea lysis on the regional scale show a spatial relationship between known= geothermal activity and (1) change in the direction of fault orientations, (2) change in the direction of extensional strain, and (3) the magnitude of extensional strain, especially fault-normal extension associated with shear strain. In contrast, the dilitation component of strain is not a significant indicator of geothermal activity in the Great Basin. Using the observed relationships between strain and structure, the NE-SW trending Humboldt structural zone (HSZ) in north-eastern Nevada is clearly identifiable as a regional geothermal target. Based on our detection of an anomalous high in fault-normal extensional strain, we identify Buffalo Valley toward the NE extent of the HSZ as a potential geothermal target to be further explored using GPS. We therefore recommend investigating Buffalo Valley With fine spatial resolution (-1 0 km rather than the current -100 h) using a dense GPS network to assess its geothermal potential, by comparison of strain-s~ucturere lationships with current Power-producing areas within the HSZ.